Ice machine including vapor-compression system

ABSTRACT

An ice machine may include a compressor, a first heat exchanger, an expansion device, an evaporator, an ice tray, and a water pump. The first heat exchanger may receive compressed working fluid from the compressor. The expansion device may receive working fluid from the first heat exchanger. The evaporator may receive working fluid from the expansion device. The ice tray may be in a heat transfer relationship with the evaporator. The ice tray may include a plurality of ice molds. The water pump may be in fluid communication with the ice molds and may be configured to pump water from a water source to the ice molds.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application claims the benefit of U.S. Provisional Application No.62/332,010, filed May 5, 2016 and U.S. Provisional Application No.62/268,249, filed Dec. 16, 2015. The entire disclosures of theapplications referenced above are incorporated by reference.

FIELD

The present disclosure relates to an ice machine (e.g., an automaticcommercial ice machine) including a vapor-compression system.

BACKGROUND

This section provides background information related to the presentdisclosure and is not necessarily prior art.

Automatic commercial ice-making machines produce batches of ice cubes atregular intervals. Such ice machines are commonly used in food service,food preservation, hotel and health service industries. Ice machinestypically include a vapor-compression system that is operable in afreeze mode and a harvest mode. In the freeze mode, thevapor-compression system freezes water in a grid plate (i.e., an icetray) formed on an evaporator of the vapor-compression system. In theharvest mode, the vapor-compression system melts a small amount of theice in the ice tray so that the ice cubes can be easily ejected from theice tray.

There is a demand in the ice machine industry to provide ice machinesthat consume less energy while maintaining or increasing ice productionlevels. The present disclosure provides an ice machine and a simulationmodel that allows ice machine designers and engineers to quicklyevaluate how changing one or more system design options and parameterscan impact the energy consumption and ice production of the ice machine.

SUMMARY

This section provides a general summary of the disclosure, and is not acomprehensive disclosure of its full scope or all of its features.

In one form, the present disclosure provides an ice machine that mayinclude a compressor, a first heat exchanger, an expansion device, anevaporator, an ice tray, and a water pump. The first heat exchanger mayreceive compressed working fluid from the compressor. The expansiondevice may receive working fluid from the first heat exchanger. Theevaporator may receive working fluid from the expansion device. The icetray may be in a heat transfer relationship with the evaporator. The icetray may include a plurality of ice molds. The water pump may be influid communication with the ice molds and may be configured to pumpwater from a water source to the ice molds. Structural characteristicsof at least one of the compressor, the first heat exchanger, theexpansion device, and the evaporator are specified based on output froma processor. The processor may receive a first set of values for a firstset of parameters of the compressor, the first heat exchanger, theexpansion device, and the evaporator. The processor may calculate asecond set of parameters of the ice machine based on at least a portionof the first set of values, a water temperature and an ambient airtemperature. The second set of parameters may correspond to operation ofthe ice machine in a freeze mode in which liquid water is cooled in theice molds by the evaporator. The processor may calculate a third set ofparameters of the ice machine based on at least a portion of the firstset of values, the water temperature and the ambient temperature. Thethird set of parameters may correspond to operation of the ice-makingmachine in a harvest mode during which a predetermined amount of ice ismelted until the ice is removed from the ice molds.

In some configurations, the ice machine includes a water sump disposedwithin the evaporator and in fluid communication with the water pump.

In some configurations, the ice machine includes a second heat exchangerincluding a first coil and a second coil. The first coil may receiveworking fluid from the first heat exchanger and may be disposed upstreamof the expansion device. The second coil may receive working fluid fromthe evaporator and may be disposed upstream of the compressor.

In another form, the present disclosure provides a method that mayinclude selecting a first set of values for a first set of parameters ofone or more hardware components of an ice-making machine; identifying awater temperature at a water inlet of the ice-making machine;identifying an ambient air temperature surrounding the ice-makingmachine; calculating a second set of parameters of the ice-makingmachine based on at least a portion of the first set of values, thewater temperature and the ambient temperature, the second set ofparameters corresponding to operation of the ice-making machine in afreeze mode in which liquid water is cooled by an evaporator; andcalculating a third set of parameters of the ice-making machine based onat least a portion of the first set of values, the water temperature andthe ambient temperature, the third set of parameters corresponding tooperation of the ice-making machine in a harvest mode during which apredetermined amount of ice is melted until the ice is removed from theevaporator.

In some configurations, the method includes selecting a second set ofvalues for the first set of parameters of the one or more hardwarecomponents; calculating the second set of parameters of the ice-makingmachine based on at least a portion of the second set of values;calculating the third set of parameters of the ice-making machine basedon at least a portion of the second set of values; and comparing resultsof the calculations of the second and third sets of parameters based onthe first values with the results of the calculations of the second andthird sets of parameters based on the second values.

In some configurations, the results include energy consumption of theice-making machine and ice production of the ice-making machine.

In some configurations, the method includes designing avapor-compression system based on the comparison of the results.

In some configurations, designing the vapor-compression system includesselecting a compressor based on the comparison of the results.

In some configurations, the first set of parameters include compressorcapacity, compressor efficiency, and/or compressor motor speed.

In some configurations, the first set of parameters include geometricparameters of the condenser and evaporator.

In some configurations, the first set of parameters include initialevaporator and condenser pressures at a startup of the ice-makingmachine.

In some configurations, the first set of parameters includes an air flowrate of a condenser fan.

In some configurations, the method includes displaying values of thesecond and third sets of parameters.

In some configurations, the second and third sets of parameters includeenergy consumption of the ice-making machine and ice production of theice-making machine.

In some configurations, the second set of parameters includes heattransfer between first and second conduits of a heat exchanger, thefirst conduit containing condensed refrigerant upstream of an expansiondevice, the second conduit receiving refrigerant downstream of theevaporator and upstream of a suction inlet of a compressor.

In some configurations, the second set of parameters includes a flowarea of an expansion device.

In some configurations, the third set of parameters includes a flow areaof a bypass control valve.

In some configurations, calculating the second and third sets ofparameters includes using an implicit solver to solving sets ofequations to satisfy Kirchhoff's first and second laws at nodes of avapor-compression system of the ice-making machine.

Further areas of applicability will become apparent from the descriptionprovided herein. The description and specific examples in this summaryare intended for purposes of illustration only and are not intended tolimit the scope of the present disclosure.

BRIEF DESCRIPTION OF THE DRAWINGS

The drawings described herein are for illustrative purposes only ofselected embodiments and not all possible implementations, and are notintended to limit the scope of the present disclosure.

FIG. 1 is a schematic representation of an ice maker;

FIG. 2 is a schematic representation of a simulation module incommunication with input and output interfaces;

FIG. 3 is a flowchart depicting an initialization process of asimulation model;

FIG. 4 is a flowchart generally outlining a freeze model of thesimulation model; and

FIG. 5 is a flowchart generally outlining a harvest model of thesimulation model.

Corresponding reference numerals indicate corresponding parts throughoutthe several views of the drawings.

DETAILED DESCRIPTION

Example embodiments will now be described more fully with reference tothe accompanying drawings.

Example embodiments are provided so that this disclosure will bethorough, and will fully convey the scope to those who are skilled inthe art. Numerous specific details are set forth such as examples ofspecific components, devices, and methods, to provide a thoroughunderstanding of embodiments of the present disclosure. It will beapparent to those skilled in the art that specific details need not beemployed, that example embodiments may be embodied in many differentforms and that neither should be construed to limit the scope of thedisclosure. In some example embodiments, well-known processes,well-known device structures, and well-known technologies are notdescribed in detail.

The terminology used herein is for the purpose of describing particularexample embodiments only and is not intended to be limiting. As usedherein, the singular forms “a,” “an,” and “the” may be intended toinclude the plural forms as well, unless the context clearly indicatesotherwise. The terms “comprises,” “comprising,” “including,” and“having,” are inclusive and therefore specify the presence of statedfeatures, integers, steps, operations, elements, and/or components, butdo not preclude the presence or addition of one or more other features,integers, steps, operations, elements, components, and/or groupsthereof. The method steps, processes, and operations described hereinare not to be construed as necessarily requiring their performance inthe particular order discussed or illustrated, unless specificallyidentified as an order of performance. It is also to be understood thatadditional or alternative steps may be employed.

When an element or layer is referred to as being “on,” “engaged to,”“connected to,” or “coupled to” another element or layer, it may bedirectly on, engaged, connected or coupled to the other element orlayer, or intervening elements or layers may be present. In contrast,when an element is referred to as being “directly on,” “directly engagedto,” “directly connected to,” or “directly coupled to” another elementor layer, there may be no intervening elements or layers present. Otherwords used to describe the relationship between elements should beinterpreted in a like fashion (e.g., “between” versus “directlybetween,” “adjacent” versus “directly adjacent,” etc.). As used herein,the term “and/or” includes any and all combinations of one or more ofthe associated listed items.

Although the terms first, second, third, etc. may be used herein todescribe various elements, components, regions, layers and/or sections,these elements, components, regions, layers and/or sections should notbe limited by these terms. These terms may be only used to distinguishone element, component, region, layer or section from another region,layer or section. Terms such as “first,” “second,” and other numericalterms when used herein do not imply a sequence or order unless clearlyindicated by the context. Thus, a first element, component, region,layer or section discussed below could be termed a second element,component, region, layer or section without departing from the teachingsof the example embodiments.

Spatially relative terms, such as “inner,” “outer,” “beneath,” “below,”“lower,” “above,” “upper,” and the like, may be used herein for ease ofdescription to describe one element or feature's relationship to anotherelement(s) or feature(s) as illustrated in the figures. Spatiallyrelative terms may be intended to encompass different orientations ofthe device in use or operation in addition to the orientation depictedin the figures. For example, if the device in the figures is turnedover, elements described as “below” or “beneath” other elements orfeatures would then be oriented “above” the other elements or features.Thus, the example term “below” can encompass both an orientation ofabove and below. The device may be otherwise oriented (rotated 90degrees or at other orientations) and the spatially relative descriptorsused herein interpreted accordingly.

The present disclosure provides a simulation model of an ice-makingmachine such as an automatic commercial ice maker 10 (shownschematically in FIG. 1), for example. As will be described in moredetail below, the simulation model enables prediction of componentconditions, loads under different operating environments, and assessmentof system design changes. The simulation model simulates transientoperation of the ice maker 10 based, in part, on generalizedcorrelations. The simulation model determines time-varying changes inproperties of the ice maker 10 and aggregates performance results as afunction of machine capacity and environmental conditions. Thesimulation model can conduct rapid “what if” analyses enabling ice makerdesigners and engineers to quickly evaluate the impact of a variety ofsystem design options including, for example, heat exchanger size, sizeand shape of finned surfaces, air flow rate, water flow rate, ambientair temperature, inlet water temperature, compressor capacity and/orefficiency for freeze and harvest cycles of the ice maker 10,refrigerants, suction-line heat exchanger properties, and/or expansionvalve properties.

As shown in FIG. 2, the simulation model may include a parameter-inputinterface 12 (e.g., a computer keyboard and/or mouse), a simulationmodule 14 (e.g., a processor), and an output interface 16 (e.g., acomputer monitor and/or printout). A user of the simulation model mayinput a plurality of actual or hypothetical system and environmentalparameters into the parameter-input interface 12. The simulation module14 may conduct the above-mentioned “what if” analyses based on theparameters input by the user. The output interface 16 may transmitand/or display the results of the analyses conducted by the simulationmodule 14 to provide the user with a model of the impact of a variety ofsystem design options.

Referring now to FIG. 1, an example ice maker 10 will be described indetail. The ice maker 10 includes a cabinet 18 housing avapor-compression system 20 and a water-handling system 22. While notspecifically shown in the figures, the cabinet 18 may include anice-cube-storage bin that holds ice cubes that have been harvestedduring operation of the ice maker 10. The ice-cube-storage bin mayinclude a door that a user can open to access the ice cubes within thebin.

The vapor-compression system 20 may include a compressor 24, a firstheat exchanger 26 (e.g., a condenser or gas cooler), a second heatexchanger 28 (e.g., a sub-cooler or suction-line heat exchanger), anexpansion device 30 (e.g., an electronic or thermostatic expansionvalve, a fixed orifice or capillary tube), and a third heat exchanger 32(e.g., an evaporator). The compressor 24 can be any suitable type ofcompressor, such as a scroll, reciprocating or rotary, for example. Thecompressor 24 may compress a working fluid (e.g., a refrigerant) from asuction pressure to a discharge pressure.

A discharge line 34 may fluidly connect the compressor 24 with the firstheat exchanger 26. A fan 27 may force ambient air across fins (notshown) of the first heat exchanger 26 to cool the working fluid flowingthrough the first heat exchanger 26. The first heat exchanger 26 mayalso be fluidly connected with a first coil 36 of the second heatexchanger 28.

The expansion device 30 is fluidly connected with the first coil 36 andan evaporator coil 38 of the third heat exchanger 32 and is disposedbetween an outlet of the first coil 36 and an inlet 37 of the evaporatorcoil 38. A second coil 40 of the second heat exchanger 28 may be fluidlyconnected with an outlet 39 of the evaporator coil 38. A suction line 42fluidly connects the second coil 40 with a suction inlet 44 of thecompressor 24.

A bypass line 46 may extend from the discharge line 34 to the inlet 37of the evaporator coil 38. A bypass control valve 48 may be disposedalong the bypass line 46 and may control fluid flow through the bypassline 46.

The water-handling system 22 may include a water-inlet valve 50, a watersump 52, a sump purge valve 54, a water pump 56 and an ice tray 58. Thewater-inlet valve 50 may be disposed on a water-supply line 59 fluidlyconnected to a water source 60 (e.g., water pipes of a building in whichthe ice maker 10 is installed). The water-inlet valve 50 may control aflow of water through the water-supply line 59 from the water source 60to the water sump 52. The sump purge valve 54 may be fluidly connectedto the water sump 52 and a drain 62 (e.g., drainage pipes of thebuilding in which the ice maker 10 is installed) and may control a flowof water from the water sump 52 to the drain 62. The sump purge valve 54can be selectively opened to purge some or all of the water from thewater sump 52.

The water pump 56 may be disposed along a water-fill line 64 fluidlyconnected to the water sump 52 and the ice tray 58. The water pump 56may selectively pump water through the water-fill line 64 from the watersump 52 to the ice tray 58. The ice tray 58 may include a plurality ofmolds 66 in which water may freeze to form ice cubes. The ice tray 58may be mounted on, integrally formed with, or otherwise situated to bein a heat transfer relationship with the evaporator coil 38 such thatheat can be exchanged between liquid water or ice in the ice tray 58 andworking fluid in the evaporator coil 38.

With continued reference to FIG. 1, operation of the ice maker 10 willbe described in detail. The ice maker 10 is operable in a freeze mode inwhich liquid water in the ice tray 58 is cooled to or beyond itsfreezing point and in a harvest mode in which ice cubes in the ice tray58 are heated to allow the ice cubes to be ejected from the ice tray 58.A control module (not shown) may control operation of the compressor 24,the expansion device 30, the bypass control valve 48, the water-inletvalve 50, the sump purge valve 54, and the water pump 56.

When the freeze mode is initiated, the water pump 56 pumps water fromthe sump 52 into the molds 66 of the ice tray 58. The water-inlet valve50 may open and close as needed to provide an adequate amount of waterto the water sump 52.

During operation in the freeze mode, the bypass control valve 48 isclosed to prevent the flow of hot discharge-pressure working fluidthrough the bypass line 46. Therefore, in the freeze mode, thedischarge-pressure working fluid discharged from the compressor 24 mayflow through the discharge line 34 to the first heat exchanger 26.

In the first heat exchanger 26, heat from the working fluid may betransferred to ambient air. From the first heat exchanger 26, theworking fluid may flow into the first coil 36 of the second heatexchanger 28. Heat from the working fluid in the first coil 36 may beabsorbed by suction-pressure working fluid in the second coil 40 of thesecond heat exchanger 28, thereby further cooling the working fluid inthe first coil 36. From the first coil 36, the working fluid may flowthrough the expansion device 30 before flowing into the evaporator coil38. Cold working fluid in the evaporator coil 38 absorbs heat from thewater in the molds 66 of the ice tray 58. After exiting the evaporatorcoil 38, the working fluid may flow through the second coil 40 of thesecond heat exchanger 28 and then flow back to the compressor 24 (viasuction inlet 44).

Once the water in the ice tray 58 is sufficiently frozen (i.e., apredetermined ice batch weight has been reached, as determined based onany of a sump water level, compressor suction pressure, thickness of iceon the ice tray 58, etc.), the ice maker 10 may be switched to theharvest mode. In the harvest mode, the bypass control valve 48 is opento allow hot discharge-pressure working fluid exiting the compressor 24to flow through the bypass line 46 and directly into the evaporator coil38. Therefore, in the harvest mode, hot working fluid in the evaporatorcoil 38 heats the ice in the ice tray 58 to melt a small amount (e.g.,5-10%) of ice in each mold 66, thereby allowing the ice cubes in the icetray 58 to fall out of the ice tray 58 by gravity (or allowing the icecubes to be forced out of the ice tray 58 by other means) into theice-cube-storage bin of the ice maker 10.

During the operation in harvest mode, water in the water sump 52 may bepurged by opening the sump purge valve 54. During the purge of the watersump 52, fresh water from the water source 60 may be flushed through thewater-handling system 22 and drained out of the water sump 52 (via thepurge valve 54) to flush any impurities out of the water-handing system22. Once the ice cubes fall out of the ice tray 58 and into theice-cube-storage bin (as determined by evaporator temperature and/ortime, for example), the water sump 52 may be filled (e.g., to a waterlevel that is 10-40% more water than is needed to make a batch of icecubes) and the ice maker 10 can switch back to the freeze mode.

While the ice maker 10 is described above as making ice cubes, it willbe appreciated that the molds 66 of the ice tray 58 can be configured tomake ice in any shape including, for example, cubes, rectangular prisms,cylinders, nuggets, flakes or crescents.

Referring now to FIGS. 2-5, operation of the simulation model will bedescribed in detail. As shown in FIG. 3, the simulation may begin withvarious parameters being input by the user into the parameter-inputinterface 12 (FIG. 2). At block 110, machine parameters may be input.Such machine parameters may include (i) a specified mass of ice M1 to beformed within the ice tray 58, (ii) physical geometric parameters Vc ofthe first heat exchanger 26 (condenser), (iii) physical geometricparameters Ve of the third heat exchanger 32 (evaporator), (iv) physicalgeometric parameters Vp of the compression mechanism of the compressor24 (e.g., displacement of the compression mechanism), (v) speed w of themotor of the compressor 24, (vi) efficiency η of the compressor 24(e.g., volumetric and/or isentropic efficiencies), (vii) throttling areaAv of the expansion device 30, (viii) gain Gv of the expansion device30, (ix) time constant TV of the expansion device 30, (x) volumetricflow rate {dot over (V)}a of air forced over the first heat exchanger 26by the fan 27, and (xi) refrigerant type.

At block 120, operating conditions may be input by the user. Theoperating conditions may include a temperature Tw of the water suppliedto the water sump 52 via the water-supply line 59 and an temperatureTair of the ambient air forced over the first heat exchanger 26 by thefan 27. At block 130, startup conditions may be input by the user. Thestartup conditions may include (i) an initial startup evaporatorpressure pe0, (ii) an initial startup condenser pressure pc0, (iii) aninitial working fluid quality xe0 (i.e., a ratio of vapor-to-liquidworking fluid) at the evaporator, and an initial working fluid qualityxc0 (i.e., a ratio of vapor-to-liquid working fluid) at the condenser.

After the above parameters are input into the parameter-input interface12, the parameters are used by the simulation module 14 to run a freezemodel 200 (i.e., a model of the freeze mode of the ice maker 10;outlined in FIG. 4) and a harvest model 300 (i.e., a model of theharvest mode of the ice maker 10; outlined in FIG. 5). The simulationmodule 14 may run implicit routines using an implicit solver (acausalmodeling) system such as SimScape, Simulink®, Modelica®, LabVIEW, etc.to solve sets of overall algebraic and differential equations as neededsuch that Kirchhoff's first and second laws are satisfied at the nodeswhere components of the ice maker 10 (i.e., components of thevapor-compression system 20 and water-handling system 22) are connected.That is, through-variables (e.g., mass flow rate and heat flow rate)should sum to zero at the nodes and the across-variables (e.g., pressureand enthalpy) at the nodes should be equal.

Referring now to FIG. 4, general steps of the freeze model 200 will bedescribed. As indicated at block 205, the freeze mode of the ice maker10 may begin with supply water (e.g., from the water source 60) at thetemperature Tw is mixed with any remaining water in the water sump 52.Block 210 increments through time (e.g., time during which thevapor-compression system 20 is operating in the freeze mode).

At block 215, the simulation module 14 determines whether a specifiedamount of water has been frozen in the ice tray 58 (e.g., based onelapsed time, evaporator temperature, etc.). If the specified amount ofwater has been frozen, then the simulation module 14 switches to theharvest model 300 (FIG. 5). If the specified amount of water has notbeen frozen, then the simulation module 14 proceeds to determine varioussystem parameters (at blocks 220-255) using the implicit routines of theimplicit solver system to solve sets of overall algebraic anddifferential equations as needed to satisfy Kirchhoff's first and secondlaws at the nodes.

Block 220 represents equations for compressor parameters used by theimplicit solver routines. For example, a mass flow rate {dot over (m)}dof working fluid delivered by the compressor 24 to the other componentsof the vapor-compression system 20 can be determined from the followingequation:

{dot over (m)}_(d)=η_(v)ωp_(cs)V_(d),

where η_(v) is volumetric efficiency of the compressor 24, ω is thecompressor motor speed, p_(cs) is the compressor suction-gas density,and V_(d) is the displacement of the compression mechanism.

A polytropic approach can be used to determine power {dot over (W)}consumed by the compressor 24. That is, the power {dot over (W)} can bedetermined from the following equation:

${{\overset{.}{W}\; k} = {\left\lbrack {\left( {k - 1} \right)/k} \right\rbrack \eta_{d}\omega \; V_{d}{p_{e}\left( {1 - \frac{p_{c}}{p_{e}}} \right)}^{{({k - 1})}/k}}},$

where k is a polytropic exponent, η_(d) is compressor efficiency, ω isthe compressor motor speed, V_(d) is the displacement of the compressionmechanism, p_(e) is evaporator pressure, and p_(c) is condenserpressure.

Alternatively, power {dot over (W)} consumed by the compressor 24 can bedetermined using the following equation:

{dot over (W)}=C ₁ +C ₂ T _(e) +C ₃ T _(c) +C ₄ T _(e) ² +C ₅ T _(e) T_(c) +C ₆ T _(c) ² +C ₇ T _(e) ³ +C ₈ T _(e) ² T _(c) +C ₉ T _(e) T _(c)² +C ₁₀ T _(c) ³,

where C₁-C₁₀ are rating coefficients for a particular compressor(published by compressor manufacturers), T_(e) is evaporator saturationtemperature, and T_(c) is condenser saturation temperature.

An energy balance on the vapor working fluid in the compressor dischargechamber can be used to determine a temperature of the working fluidT_(d) exiting the compressor 24. An empirical compressor shell lossfactor f_(q) can be used to compensate for heat transfer through thecompressor shell wall to the ambient air.

Blocks 225 and 230 represent equations for air-side and refrigerant-sidecondenser parameters used by the implicit solver routines. The condenser(i.e., the first heat exchanger 26) can be modeled by dividing the totalvolume of the condenser into N discrete elements along its length andusing a finite-difference method. Condenser heat rejection {dot over(Q)}_(c) can be determined using the following equation:

{dot over (Q)} _(c)=Σ_(i=1) ^(N)∈_(c) C _(pc)(T _(ci) −T _(a)),

where ∈_(c) is condenser effectiveness, C_(pc) is condenser heatcapacity, T_(a) is ambient air temperature, and T_(ci) is the workingfluid temperature in the i^(th) element of the condenser. Appropriatemodels for the heat transfer correlations may be implemented that dependon the flow rate {dot over (V)}_(a) of air forced over the condenser bythe fan 27, condenser fin material, and condenser fin geometry (e.g.,smooth, corrugated, wavy and louvered). Refrigerant properties withinthe condenser may be governed by a conservation of refrigerant mass andenergy along with pressure drop due to friction. These equations may beintegrated to remove the spatial dependence, resulting in alumped-parameter time-based ordinary differential equation.

Block 235 represents a model of the second heat exchanger 28 (i.e., theliquid-line/suction-line heat exchanger) used by the implicit solverroutines. The heat flow rate {dot over (Q)}_(s) may be determinedbetween the compressor suction line (i.e., the second coil 40 of thesecond heat exchanger 28) and the condenser liquid line (i.e., the firstcoil 36 of the second heat exchanger 28) at a temperature T_(cl) of theworking fluid within the condenser liquid line. The heat flow rate {dotover (Q)}_(s) may be determined using the following equation:

{dot over (Q)} _(s) =h _(s) L _(s) D _(s)(T _(cs) −T _(cl)),

where T_(cs) is a temperature of the working fluid within the compressorsuction line (i.e., the second coil 40), T_(cl) is a temperature of theworking fluid within the condenser liquid line (i.e., the first coil36), h_(s) is an appropriate heat transfer coefficient for the secondheat exchanger 28, L_(s) is an effective length over which the first andsecond coils 36, 40 are in a heat transfer relationship with each other,and D_(s) is an effective tube size (e.g., diameter) of the coils 36,40.

Block 240 represents equations for expansion device parameters used bythe implicit solver routines. The expansion device 30 restricts flow andcreates a pressure differential between the evaporator and thecondenser. Therefore, a mass flow rate {dot over (m)}_(v) through theexpansion device 30 can be determined using the following equation:

{dot over (m)} _(v) =A _(v)√{square root over (2ρ_(v)(p _(c) −p _(e)))},

where ρ_(v) is a density of the working fluid through the expansiondevice 30, p_(c) is condenser pressure, p_(e) is evaporator pressure,and A_(v) is the effective flow area (throttling area) through theexpansion device 30.

The effective flow area A_(v) through the expansion device 30 is fixedfor orifice and capillary tube expansion devices. For thermal expansionvalves and electronic expansion valves, a mechanical or electricalfeedback system changes the effective flow area A_(v) to maintain apredetermined evaporator superheat. The effective flow area A_(v) can bedetermined based on the feedback gain G_(v) and time constant τ_(v) ofthe expansion device 30 according to the following equation:

A _(v) =A _(nom) +G _(v)[(T _(b) −T _(e))−ΔT _(sh)],

where T_(b) is a thermal sensing element (e.g., a thermo-bulb)temperature, ΔT_(sh) is the evaporator superheat (i.e., a differencebetween the saturated evaporator temperature and a temperature ofworking fluid exiting the evaporator), and A_(nom) is nominal flow areaof the expansion device 30 (which can be input by the user). Since thefeedback for a thermal expansion valve is mechanical (i.e., atemperature response for the thermal sensing element), the response lagcan be modeled by the following equation:

dT _(b) /dt=(T _(b) −T _(ev))/τ_(v),

where T_(ev) is a temperature of working fluid exiting the evaporator.

Blocks 245, 250 and 255 represent equations including water-side andrefrigerant-side evaporator parameters and ice-formation parameters usedby the implicit solver routines. The refrigerant side of the evaporatorcan be modeled in a similar manner as the refrigerant side of thecondenser, i.e., by dividing the total volume of the evaporator into Ndiscrete elements along its length and using a finite-difference method.Evaporator heat rejection {dot over (Q)}_(e) can be determined using thefollowing equation:

{dot over (Q)} _(e)=Σ_(i=1) ^(N)∈_(e) C _(pe)(T _(g) −T _(ei)),

where ∈_(e) is evaporator effectiveness, C_(pe) is evaporator heatcapacity, T_(g) is a temperature of the ice tray 58, and T_(ei) is theworking fluid temperature in the i^(th) element of the evaporator.

Heat transfer from ice in the ice tray 58 and heat transfer into theevaporator includes heat transfer through liquid water, ice, the icetray 58 and refrigerant. The heat flow from the ice tray 58 to the icemay be determined using the following equation:

{dot over (Q)} _(l) =kA _(e)(T _(l) −T _(g))/s+h _(w) A _(e)(T _(w) −T_(l)),

where k is the thermal conductivity of ice, A_(e) is the surface area ofthe ice tray 58 in contact with the water and ice, s is the thickness ofthe ice, h_(w) is the convection coefficient for a flowing liquid over aplate, T_(w) is a temperature of the water, and T_(l) is a temperatureof the ice. Thickness of the ice (s) is zero at the start of the freezecycle and can be considered proportional to the cumulative evaporatorheat transfer given by Σ{dot over (Q)}_(e)Δt.

At block 260, the simulation module 14 determines whether there isconvergence at the nodes (i.e., whether the through-variables (e.g.,mass flow rate and heat flow rate) sum to zero at the nodes and theacross-variables (e.g., pressure and enthalpy) at the nodes are equal).The simulation module 14 runs the implicit routines using the implicitsolver system to solve sets of the above equations (e.g., the equationsdescribed above with respect to blocks 220-255) as needed until there isconvergence at the nodes (i.e., Kirchhoff's first and second laws aresatisfied at the nodes).

Once the sets of equations are solved for convergence at the nodes, thesimulation module 14 loops back to block 210, where time (t) isincremented by a predetermined step. Thereafter, the freeze model 200 isrepeated until the simulation module 14 determines at block 215 that thepredetermined amount of ice has formed. Once the predetermined amount ofice has formed, the simulation module 14 switches to the harvest model300 to model operation of the ice maker 10 in the harvest mode.

Referring now to FIG. 5, general steps of the harvest model 300 will bedescribed. At block 305, the simulation module 14 increments throughtime (e.g., time during which the vapor-compression system 20 isoperating in the harvest mode).

At block 310, the simulation module 14 determines whether a specifiedamount of ice in the ice tray 58 has melted (e.g., based on elapsedtime, evaporator temperature, etc.). If the specified amount of ice hasmelted, then the simulation module 14 switches back to the freeze model200. If the specified amount of ice has not melted, then the simulationmodule 14 proceeds to determine various system parameters (at blocks315-335) using the implicit routines of the implicit solver system tosolve sets of overall algebraic and differential equations as needed tosatisfy Kirchhoff's first and second laws at the nodes.

Block 315 represents equations for compressor parameters used by theimplicit solver routines. These equations may include the equationsdescribed above with respect to block 220.

Block 320 represents equations used by the implicit solver routines thatinclude parameters of the bypass control valve 48. As described above,during the harvest mode, the bypass control valve 48 is open to allowthe refrigerant to bypass the first and second heat exchangers 26, 28and the expansion device 30, and instead, flow directly to the thirdheat exchanger 32 (the evaporator). A mass flow rate {dot over (m)}h ofrefrigerant through the bypass control valve 48 can be determined usingthe following equation:

{dot over (m)} _(h) =A _(h)√{square root over (2ρ_(d)(p _(d) −p _(e)))},

where ρ_(d) is a density of the refrigerant that is discharged from thecompressor 24, p_(d) is the pressure of the refrigerant that isdischarged from the compressor 24, p_(e) is evaporator pressure, andA_(h) is the effective flow area (throttling area) through the bypasscontrol valve 48.

Blocks 325-335 represent equations for compressor parameters used by theimplicit solver routines. These equations may include the equationsdescribed above with respect to block 220.

Blocks 325, 330 and 335 represent equations used by the implicit solverroutines that model evaporator parameters and heat added to the iceduring the harvest mode. These equations may include the equationsdescribed above with respect to blocks 245, 250, 255.

At block 340, the simulation module 14 determines whether there isconvergence at the nodes (i.e., whether the through-variables (e.g.,mass flow rate and heat flow rate) sum to zero at the nodes and theacross-variables (e.g., pressure and enthalpy) at the nodes are equal).The simulation module 14 runs the implicit routines using the implicitsolver system to solve sets of the above equations (e.g., the equationsdescribed above with respect to blocks 315-335) as needed until there isconvergence at the nodes (i.e., Kirchhoff's first and second laws aresatisfied at the nodes).

Once the sets of equations are solved for convergence at the nodes, thesimulation module 14 loops back to block 305, where time (t) isincremented by a predetermined step. Thereafter, the harvest model 300is repeated until the simulation module 14 determines at block 310 thatthe predetermined amount of ice has melted. Once the predeterminedamount of ice has melted, the simulation module 14 resets to the icemass to zero at block 345 (i.e., the ice is ejected from the ice tray 58once the predetermined amount of ice melts) and then switches back tothe freeze model 200 to model another operation cycle of the ice maker10 in the freeze mode.

The above process of modeling the freeze and harvest modes using thefreeze and harvest models 200, 300 may be repeated for a predeterminednumber of cycles. The simulation module 14 may calculate the totalenergy consumption of the ice maker 10 and the total amount (e.g., mass)of ice produced by the ice maker 10 during the predetermined number ofcycles and/or energy consumption and amount of ice produced per cycle.The energy consumption and ice production data may be communicated tothe output interface 16, which can display and/or print this data forthe user. Additionally, the simulation module 14 can determine a totalfreeze time and a total harvest time for the predetermined number ofcycles and/or freeze time and harvest time per cycle, and communicatethat data to the output interface 16 for the user to view.

After running the simulation model through the predetermined number ofcycles, the user of the simulation model can then change one or more ofthe input parameters (e.g., the parameters input by the user at blocks110, 120, 130) and run the simulation model again for the predeterminednumber of cycles. In this manner, the user can compare the simulationresults to evaluate whether and how the user's parameter change(s)benefited or hindered the performance of the ice maker 10. This processcan be repeated any number of times to assist the user in designing amore energy efficient and/or more productive ice maker.

Results from the simulation model described above were compared withdata measured during operation of a fully instrumented 500 poundcapacity ice maker. The simulation results and measured data include (1)cycle time (i.e., duration of freeze and harvest cycles), (2) energyinput per 100 pounds of ice, and (3) energy usage during 24 hours ofoperation. The simulation results were accurate to within 5% of theactual measured data.

As described above, the simulation model of the present disclosureallows ice maker designers and engineers to quickly evaluate the impactof a variety of system design options including, for example, heatexchanger size, size and shape of finned surfaces, air flow rate, waterflow rate, ambient air temperature, inlet water temperature, compressorcapacity and/or efficiency, refrigerants, suction-line heat exchangerproperties, and/or expansion valve properties.

The implicit solver system (such as SimScape, Simulink®, Modelica®,LabVIEW, etc.) of the simulation model 14 uses acausal modeling and doesnot utilize a predetermined calculation procedure to solve the sets ofthe above equations. Rather, the steps for solving the sets of equationsfor convergence at the nodes may be determined on a case-by-case basis.

The implicit solver may determine values for all of the system variablesthat satisfy the model equations based on the user-supplied initialconditions. The user-supplied values specified during the initializationsteps may not be the actual values of the respective variables, butrather their target values at the beginning of the simulation (time=0).Depending on the results of the solve, some of the targets may or maynot be satisfied.

After computing the initial conditions, or after a subsequent event(e.g., a discontinuity resulting from a bypass valve opening, forexample), the implicit solver performs a transient initialization. Thetransient initialization may fix dynamic variables and solves foralgebraic variables and derivatives of dynamic variables. The goal ofthe transient initialization is to provide a consistent set of initialconditions for the transient solve phase (e.g., the phase in which theimplicit solver solves the equations). In the transient solve phase,continuous differential equations are integrated in time to compute thevariables as a function of time. The implicit solver continues toperform the simulation according to the results of the transient solveuntil the solver encounters an event, such as an ice harvest. If thesolver encounters an event, the solver returns to the phase of thetransient initialization, and then back to the transient solve phase.The cycle continues until the end of the simulation.

The foregoing description is merely illustrative in nature and is in noway intended to limit the disclosure, its application, or uses. Thebroad teachings of the disclosure can be implemented in a variety offorms. Therefore, while this disclosure includes particular examples,the true scope of the disclosure should not be so limited since othermodifications will become apparent upon a study of the drawings, thespecification, and the following claims. It should be understood thatone or more steps within a method may be executed in different order (orconcurrently) without altering the principles of the present disclosure.Further, although each of the embodiments is described above as havingcertain features, any one or more of those features described withrespect to any embodiment of the disclosure can be implemented in and/orcombined with features of any of the other embodiments, even if thatcombination is not explicitly described. In other words, the describedembodiments are not mutually exclusive, and permutations of one or moreembodiments with one another remain within the scope of this disclosure.

Spatial and functional relationships between elements (for example,between modules) are described using various terms, including“connected,” “engaged,” “interfaced,” and “coupled.” Unless explicitlydescribed as being “direct,” when a relationship between first andsecond elements is described in the above disclosure, that relationshipencompasses a direct relationship where no other intervening elementsare present between the first and second elements, and also an indirectrelationship where one or more intervening elements are present (eitherspatially or functionally) between the first and second elements. Asused herein, the phrase at least one of A, B, and C should be construedto mean a logical (A OR B OR C), using a non-exclusive logical OR, andshould not be construed to mean “at least one of A, at least one of B,and at least one of C.”

In the figures, the direction of an arrow, as indicated by thearrowhead, generally demonstrates the flow of information (such as dataor instructions) that is of interest to the illustration. For example,when element A and element B exchange a variety of information butinformation transmitted from element A to element B is relevant to theillustration, the arrow may point from element A to element B. Thisunidirectional arrow does not imply that no other information istransmitted from element B to element A. Further, for information sentfrom element A to element B, element B may send requests for, or receiptacknowledgements of, the information to element A.

In this application, including the definitions below, the term ‘module’or the term ‘controller’ may be replaced with the term ‘circuit.’ Theterm ‘module’ may refer to, be part of, or include processor hardware(shared, dedicated, or group) that executes code and memory hardware(shared, dedicated, or group) that stores code executed by the processorhardware.

The module may include one or more interface circuits. In some examples,the interface circuits may include wired or wireless interfaces that areconnected to a local area network (LAN), the Internet, a wide areanetwork (WAN), or combinations thereof. The functionality of any givenmodule of the present disclosure may be distributed among multiplemodules that are connected via interface circuits. For example, multiplemodules may allow load balancing. In a further example, a server (alsoknown as remote, or cloud) module may accomplish some functionality onbehalf of a client module.

The term code, as used above, may include software, firmware, and/ormicrocode, and may refer to programs, routines, functions, classes, datastructures, and/or objects. Shared processor hardware encompasses asingle microprocessor that executes some or all code from multiplemodules. Group processor hardware encompasses a microprocessor that, incombination with additional microprocessors, executes some or all codefrom one or more modules. References to multiple microprocessorsencompass multiple microprocessors on discrete dies, multiplemicroprocessors on a single die, multiple cores of a singlemicroprocessor, multiple threads of a single microprocessor, or acombination of the above.

Shared memory hardware encompasses a single memory device that storessome or all code from multiple modules. Group memory hardwareencompasses a memory device that, in combination with other memorydevices, stores some or all code from one or more modules.

The term memory hardware is a subset of the term computer-readablemedium. The term computer-readable medium, as used herein, does notencompass transitory electrical or electromagnetic signals propagatingthrough a medium (such as on a carrier wave); the term computer-readablemedium is therefore considered tangible and non-transitory. Non-limitingexamples of a non-transitory computer-readable medium are nonvolatilememory devices (such as a flash memory device, an erasable programmableread-only memory device, or a mask read-only memory device), volatilememory devices (such as a static random access memory device or adynamic random access memory device), magnetic storage media (such as ananalog or digital magnetic tape or a hard disk drive), and opticalstorage media (such as a CD, a DVD, or a Blu-ray Disc).

The apparatuses and methods described in this application may bepartially or fully implemented by a special purpose computer created byconfiguring a general purpose computer to execute one or more particularfunctions embodied in computer programs. The functional blocks andflowchart elements described above serve as software specifications,which can be translated into the computer programs by the routine workof a skilled technician or programmer.

The computer programs include processor-executable instructions that arestored on at least one non-transitory computer-readable medium. Thecomputer programs may also include or rely on stored data. The computerprograms may encompass a basic input/output system (BIOS) that interactswith hardware of the special purpose computer, device drivers thatinteract with particular devices of the special purpose computer, one ormore operating systems, user applications, background services,background applications, etc.

The computer programs may include: (i) descriptive text to be parsed,such as HTML (hypertext markup language), XML (extensible markuplanguage), or JSON (JavaScript Object Notation) (ii) assembly code,(iii) object code generated from source code by a compiler, (iv) sourcecode for execution by an interpreter, (v) source code for compilationand execution by a just-in-time compiler, etc. As examples only, sourcecode may be written using syntax from languages including C, C++, C#,Objective-C, Swift, Haskell, Go, SQL, R, Lisp, Java®, Fortran, Perl,Pascal, Curl, OCaml, Javascript®, HTML5 (Hypertext Markup Language 5threvision), Ada, ASP (Active Server Pages), PHP (PHP: HypertextPreprocessor), Scala, Eiffel, Smalltalk, Erlang, Ruby, Flash®, VisualBasic®, Lua, MATLAB, SIMULINK, and Python®.

None of the elements recited in the claims are intended to be ameans-plus-function element within the meaning of 35 U.S.C. §112(f)unless an element is expressly recited using the phrase “means for” or,in the case of a method claim, using the phrases “operation for” or“step for.”

What is claimed is:
 1. An ice machine comprising: a compressor; a firstheat exchanger receiving compressed working fluid from the compressor;an expansion device receiving working fluid from the first heatexchanger; an evaporator receiving working fluid from the expansiondevice; an ice tray in a heat transfer relationship with the evaporator,the ice tray including a plurality of ice molds; and a water pump influid communication with the ice molds and configured to pump water froma water source to the ice molds, wherein structural characteristics ofat least one of the compressor, the first heat exchanger, the expansiondevice, and the evaporator are specified based on output from aprocessor, the processor receiving a first set of values for a first setof parameters of the compressor, the first heat exchanger, the expansiondevice, and the evaporator, the processor calculating a second set ofparameters of the ice machine based on at least a portion of the firstset of values, a water temperature and an ambient air temperature, thesecond set of parameters corresponding to operation of the ice machinein a freeze mode in which liquid water is cooled in the ice molds by theevaporator, and the processor calculating a third set of parameters ofthe ice machine based on at least a portion of the first set of values,the water temperature and the ambient temperature, the third set ofparameters corresponding to operation of the ice machine in a harvestmode during which a predetermined amount of ice is melted until the iceis removed from the ice molds.
 2. The ice machine of claim 1, furthercomprising a water sump disposed within the evaporator and in fluidcommunication with the water pump.
 3. The ice machine of claim 1,further comprising a second heat exchanger including a first coil and asecond coil, the first coil receiving working fluid from the first heatexchanger and disposed upstream of the expansion device, the second coilreceiving working fluid from the evaporator and disposed upstream of thecompressor.
 4. The ice machine of claim 1, wherein the first set ofparameters includes one or more of a compressor capacity, compressorefficiency, compressor motor speed, geometric parameters of the firstheat exchanger and the evaporator, initial pressures of the evaporatorand the first heat exchanger at a startup of the ice machine, and/or anair flow rate of a condenser fan.
 5. The ice machine of claim 1, furthercomprising displaying values of the second and third sets of parameters.6. The ice machine of claim 1, wherein the second and third sets ofparameters include energy consumption of the ice-making machine and iceproduction of the ice-making machine.
 7. The ice machine of claim 1,wherein the second set of parameters includes heat transfer betweenfirst and second conduits of a heat exchanger, the first conduitcontaining condensed refrigerant upstream of an expansion device, thesecond conduit receiving refrigerant downstream of the evaporator andupstream of a suction inlet of a compressor.
 8. The ice machine of claim1, wherein the second set of parameters includes a flow area of anexpansion device, and wherein the third set of parameters includes aflow area of a bypass control valve.
 9. A method comprising: selecting afirst set of values for a first set of parameters of one or morehardware components of an ice-making machine; identifying a watertemperature at a water inlet of the ice-making machine; identifying anambient air temperature surrounding the ice-making machine; calculatinga second set of parameters of the ice-making machine based on at least aportion of the first set of values, the water temperature and theambient temperature, the second set of parameters corresponding tooperation of the ice-making machine in a freeze mode in which liquidwater is cooled by an evaporator; and calculating a third set ofparameters of the ice-making machine based on at least a portion of thefirst set of values, the water temperature and the ambient temperature,the third set of parameters corresponding to operation of the ice-makingmachine in a harvest mode during which a predetermined amount of ice ismelted until the ice is removed from the evaporator.
 10. The method ofclaim 9, further comprising: selecting a second set of values for thefirst set of parameters of the one or more hardware components;calculating the second set of parameters of the ice-making machine basedon at least a portion of the second set of values; calculating the thirdset of parameters of the ice-making machine based on at least a portionof the second set of values; and comparing results of the calculationsof the second and third sets of parameters based on the first valueswith the results of the calculations of the second and third sets ofparameters based on the second values.
 11. The method of claim 10,wherein the results include energy consumption of the ice-making machineand ice production of the ice-making machine.
 12. The method of claim11, further comprising designing a vapor-compression system based on thecomparison of the results.
 13. The method of claim 12, wherein designingthe vapor-compression system includes selecting a compressor based onthe comparison of the results.
 14. The method of claim 9, wherein thefirst set of parameters include one or more of a compressor capacity,compressor efficiency, compressor motor speed, geometric parameters of acondenser and the evaporator, an initial evaporator and condenserpressures at a startup of the ice-making machine, and/or an air flowrate of a condenser fan.
 15. The method of claim 9, further comprisingdisplaying values of the second and third sets of parameters.
 16. Themethod of claim 9, wherein the second and third sets of parametersinclude energy consumption of the ice-making machine and ice productionof the ice-making machine.
 17. The method of claim 9, wherein the secondset of parameters includes heat transfer between first and secondconduits of a heat exchanger, the first conduit containing condensedrefrigerant upstream of an expansion device, the second conduitreceiving refrigerant downstream of the evaporator and upstream of asuction inlet of a compressor.
 18. The method of claim 9, wherein thesecond set of parameters includes a flow area of an expansion device.19. The method of claim 9, wherein the third set of parameters includesa flow area of a bypass control valve.
 20. The method of claim 9,wherein calculating the second and third sets of parameters includesusing an implicit solver to solving sets of equations to satisfyKirchhoff's first and second laws at nodes of a vapor-compression systemof the ice-making machine.